Technical Field
The invention relates to a conveying frame for a conveyor system, to a conveyor system, and to a method for operating a conveyor system.
Prior Art
Conveyor systems are used in manufacturing, in which conveying frames are transported along a conveying segment, and the actual goods to be conveyed are accommodated on these conveying frames. Frequently the case exists that the goods to be conveyed must be accessible at various points of the conveying segment at differing heights, for example when assembly work must be carried out. For this purpose, the conveying frames often comprise lift tables or are designed as lift tables.
The lift tables include an electromechanical drive, which allows the goods being conveyed to be raised or lowered. Electromechanical drives shall be understood to mean drive systems that are driven by an electric motor, which is mechanically coupled to the lift table.
Different types of conveying frames are known; for example, the automotive industry refers to these in particular as skids. Hereafter, the term ‘conveying frame’ also refers to skids that comprise a lift table. In this connection, ‘conveying frame’ shall also refer to what are known as lift suspension fixtures, in which the actual lift table is integrated in a conveying frame designed as a suspension rack, which is transported suspended on a rail construction.
The conveying frames are transported in the conveyor system either on conveyor belts; however, at times rail systems, chain conveyors, and friction roller drives or the like are also used.
All these systems have in common that a power supply system must be present to supply the lift table with electrical energy so as to enable operation of the lift table. The related art essentially teaches two solutions in this regard, which are the supply via collectors and conductor lines on the one hand, and contactless energy transmission by inductive coupling on the other hand.
Power supply is complex since it has to be designed in such a way that the theoretically possible simultaneous operation of the lift tables is a load that can be managed.
In practice, the raising and lowering processes account for only a fraction of the operating time, which is to say, the overall power supply is generally not utilized the majority of the time.
Even though the utilization of the power supply systems is minimal, the costs for these often account for 25% to 35% of the overall costs of such a system.
US 2004/0054435 A1 discloses a conveyor system in which the conveying frames each have a dedicated conveyor drive assembly that is powered by a rechargeable battery. The conveying frames can move independently through the conveyor system as a result of this drive assembly. The conveyor drive assemblies of the individual conveying frames are supplied with energy by rechargeable batteries, which are an integral part of the conveying frames. Such conveyor systems make it possible to supply the power supply system of the lift drives for lift tables likewise with electrical energy from the rechargeable batteries that are provided for operating the conveyor drive assemblies of the individual conveying frames. This is possible since the maximum electrical power consumption of the lift drive of a lift table is lower than the maximum electrical power consumption for which the rechargeable batteries must be designed in such conveying frames to cover the demand for electrical energy of the conveyor drive assemblies. However, the disadvantage of such a system is that it is necessary to install rechargeable batteries having accordingly high capacities in the conveying frames, so as to supply sufficient electrical power for the conveyor drive assembly. This likewise results in high costs, which is why such systems offer no advantage, or at least no noteworthy advantage, from a cost perspective over the above-described systems, in which the conveying frames do not comprise a dedicated conveyor drive, but are moved solely by stationary conveying devices.